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Astronomers find 8 new planets in Goldilocks zone

Two of the newly-discovered planets are the most similar to Earth of any known exoplanets to date.

This artist’s conception depicts an Earth-like planet orbiting an evolved star that has formed a stunning “planetary nebula.” Earlier in its life, this planet may have been like one of the eight newly discovered worlds orbiting in the habitable zones of their stars. Image credit: David A. Aguilar (CfA)

Astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) announced this week that they have found eight new planets in the so-called “Goldilocks” zone – that is, each world is orbiting its star at a distance that would allow liquid water to exist on the planet’s surface. Most of these planets have a good chance of being rocky, like Earth, say the researchers.

This doubles the number of small planets believed to be in the habitable zone of their parent stars. To be in the habitable zone, an exoplanet must receive about as much sunlight as Earth. Too much, and any water would boil away as steam. Too little, and water will freeze solid.

Among these eight, the team identified two that are the most similar to Earth of any known exoplanets to date.

The two most Earth-like planets of the group are Kepler-438b and Kepler-442b. Both orbit red dwarf stars that are smaller and cooler than our sun. Kepler-438b is located 470 light-years from Earth, while the more distant Kepler-442b is 1,100 light-years away. Kepler-438b circles its star every 35 days, while Kepler-442b completes one orbit every 112 days.

With a diameter just 12 percent bigger than Earth, Kepler-438b has a 70-percent chance of being rocky, according to the team’s calculations. Kepler-442b is about one-third larger than Earth, but still has a 60-percent chance of being rocky.

Kepler-438b receives about 40 percent more light than Earth. (In comparison, Venus gets twice as much solar radiation as Earth.) As a result, the team calculates it has a 70 percent likelihood of being in the habitable zone of its star.

Kepler-442b get about two-thirds as much light as Earth. The scientists give it a 97 percent chance of being in the habitable zone.

Study co-author David Kipping of the CfA said:

We don’t know for sure whether any of the planets in our sample are truly habitable. All we can say is that they’re promising candidates.

These findings were announced January 6, 2015 in a press conference at a meeting of the American Astronomical Society.

Bottom line: On January 6, 2015, astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) announced that they have found eight new planets in the so-called “Goldilocks” zone. Most of these planets have a good chance of being rocky, like Earth, say the researchers.Among these eight, the team identified two that are the most similar to Earth of any known exoplanets to date.